Ankle replacement apparatus and method

Abstract

In some exemplary embodiments, an ankle replacement prosthesis includes a tibial component which provides a convex bearing surface, and a talar component which provides a concave bearing surface configured to interface with the convex bearing surface of the tibial component to provide a joint of the ankle replacement prosthesis. The tibial component is configured to be attached to a patient's tibia and the talar component is configured to be attached to the patient's talus.

What is claimed is: 
     
       1. An ankle replacement prosthesis, comprising:
 a tibial component comprising a tibial bearing component providing a convex bearing surface and a tibial attachment component configured to be attached to a patient's tibia, the tibial bearing component and the tibial attachment component configured to be secured to one another by a pivotal attachment that allows pivoting or rotation between the tibial bearing component and the tibial attachment component relative to each other after implanting of the ankle replacement prosthesis to emulate natural lateral motion of an ankle, wherein the pivotal attachment comprises:
 a post on the tibial attachment component; 
 an aperture in the tibial bearing component and configured to receive the post; 
 a snap-fit connection including a lip formed in the aperture and configured to snap-fit the post into the aperture and to allow pivoting or rotation between the tibial bearing component and the tibial attachment component about an axis of loading, the axis of loading being parallel to a direction the post is snap-fitted into the aperture; and 
 
 a talar component configured to be attached to the patient's talus, the talar component providing a concave bearing surface configured to interface with the convex bearing surface of the tibial component to provide a joint of the ankle replacement prosthesis, the talar component comprising: 
 a top portion defining the concave bearing surface; 
 a bottom portion configured for fixation to the patient's talus, the bottom portion having:
 a flat bottom surface arranged opposite the concave bearing surface; 
 a mounting post extending from the flat bottom surface; and 
 anterior and posterior angled bottom surfaces arranged adjacent to the flat bottom surface and at an angle with respect to the flat bottom surface; 
 
 flat edge portions extending from posterior and anterior sides of the top portion to the bottom portion, the flat edge portions and the anterior and posterior angled bottom surfaces defining anterior and posterior fastening flanges; and 
 a plurality of screw receiving apertures each configured to receive a screw fastener, wherein at least one screw receiving aperture extends through the posterior fastening flange in a posterior to anterior direction to direct at least one of the plurality of screw fasteners toward a talar neck of the talus. 
 
     
     
       2. The ankle replacement prosthesis of  claim 1 , wherein the tibial component further comprises a cylinder member extending in a first direction and configured to be inserted into the patient's tibia, the cylinder member having at least one aperture or opening to allow bony ingrowth of the tibia into the cylinder member of the tibial component. 
     
     
       3. The ankle replacement prosthesis of  claim 1 , wherein the tibial component and talar component comprise carbon-fiber-reinforced (CFR) polyetheretherketone (PEEK) and wherein the bearing surfaces of the tibial component and the talar component comprise ultra-high-molecular-weight polyethylene (UHMWPE). 
     
     
       4. The ankle replacement prosthesis of  claim 1 , wherein the aperture of the pivotal attachment has a first aperture diameter at an aperture entrance, and a second aperture diameter, larger than the first aperture diameter, beyond the aperture entrance, the lip providing a retaining surface formed between the aperture entrance and aperture areas having the second aperture diameter, and wherein the post has a first portion having a first post diameter and a second portion having a second post diameter, smaller than the first post diameter, wherein when the post is fully received in the aperture to allow pivoting or rotation between the tibial bearing component and the tibial attachment component, the first post portion is retained in the aperture by the retaining surface of the lip. 
     
     
       5. The ankle replacement prosthesis of  claim 1 , wherein the post of the pivotal attachment is positioned on a bottom of a base portion of the tibial attachment component, and wherein the aperture is positioned in the tibial bearing component. 
     
     
       6. The ankle replacement prosthesis of  claim 1 , wherein the at least one screw receiving aperture that extends through the posterior fastening flange extends at an angle between 50 degrees and 60 degrees relative to the flat edge portion of the posterior fastening flange. 
     
     
       7. The ankle replacement prosthesis of  claim 1 , wherein the at least one screw receiving aperture that extends through the posterior fastening flange extends at an angle of 55 degrees relative to the flat edge portion of the posterior fastening flange. 
     
     
       8. The ankle replacement prosthesis of  claim 1 , wherein two screw receiving apertures extend through the anterior fastening flange in an anterior to posterior direction. 
     
     
       9. The ankle replacement prosthesis of  claim 8 , wherein the two screw receiving apertures that extend through the anterior fastening flange exit the anterior angled bottom surface at opposite sides of the mounting post. 
     
     
       10. The ankle replacement prosthesis of  claim 9 , wherein the at least one screw receiving aperture that extends through the posterior fastening flange exits the posterior angled bottom surface in a direction toward the mounting post. 
     
     
       11. The ankle replacement prosthesis of  claim 1 , wherein the post has a cylindrical shape that includes a first diameter portion and a second diameter portion, the first diameter portion being larger than the second diameter portion;
 wherein the aperture has a circular shape that includes a first diameter area and a second diameter area, the second diameter area being larger than the first diameter area; and 
 wherein the lip snap-fits the post into the aperture by capturing the first diameter portion of the post in the second diameter area of the aperture. 
 
     
     
       12. An ankle replacement prosthesis comprising:
 a tibial component comprising a tibial bearing component providing a convex bearing surface and a tibial attachment component, the tibial bearing component and the tibial attachment component configured to be secured to one another by a pivotal attachment that allows pivoting or rotation between the tibial bearing component and the tibial attachment component relative to each other, wherein the pivotal attachment comprises:
 a post on the tibial attachment component having a larger diameter portion and a smaller diameter portion; 
 an aperture in the tibial bearing component configured to receive the post; and 
 a snap-fit connection including a lip formed in the aperture, the snap-fit connection configured to snap-fit the post into the aperture in a direction parallel to an axis of loading and to allow pivoting or rotation between the tibial bearing component and the tibial attachment component about the axis of loading, wherein the lip of the snap-fit connection is configured to retain the larger diameter portion of the post in the aperture; and 
 
 a talar component comprising:
 a top portion comprising:
 a concave bearing surface configured to interface with the convex bearing surface of the tibial component to permit anterior and posterior pivoting of the talar component relative to the tibial component to provide a joint of the ankle replacement prosthesis; and 
 sidewalls adjacent to the concave bearing surface to limit side-to-side movement of the talar component relative to the tibial component; 
 
 a bottom portion configured for fixation to a talus, the bottom portion comprising:
 a flat bottom surface arranged opposite the concave bearing surface; 
 a mounting post extending from the flat bottom surface; and 
 anterior and posterior angled bottom surfaces arranged adjacent to the flat bottom surface, and projecting at an angle away from the flat bottom surface; 
 
 flat edge portions extending along anterior and posterior sides of the talar component and extending from the top portion to the bottom portion of the talar component, wherein the flat edge portions and the anterior and posterior angled bottom surfaces define anterior and posterior fastening flanges; 
 first and second screw receiving apertures extending through the anterior fastening flange from the flat edge portion at the anterior side of the talar component to the anterior angled bottom surface of the talar component, the first and second screw receiving apertures being spaced apart from each other and extending in an anterior to posterior direction; and 
 a third screw receiving aperture extending through the posterior fastening flange from the flat edge portion at the posterior side of the talar component to the posterior angled bottom surface of the talar component, the third screw receiving aperture being disposed at an angle relative to the flat edge portion at the posterior side of the talar component of between 50 degrees and 60 degrees and extending in a posterior to anterior direction. 
 
 
     
     
       13. The ankle replacement prosthesis of  claim 1 , further comprising a plurality of screw fasteners, wherein a screw fastener received by the third screw receiving aperture that extends through the posterior fastening flange is directed toward a talar neck.